Pathogenic Escherichia coli

Pathogenic Escherichia coli (E. coli) are a group of bacteria that can cause various diseases in humans, ranging from mild gastrointestinal infections to life-threatening conditions. E. coli is a diverse group of bacteria, but only certain strains are pathogenic. These pathogenic strains are categorized based on their distinct mechanisms of pathogenicity, clinical symptoms, and outcomes.

Types of Pathogenic E. coli

The pathogenic strains of E. coli can be classified into several categories, including:

• Enteropathogenic E. coli (EPEC): Causes diarrhea in infants, primarily in low-income countries. EPEC adherence to intestinal cells leads to the destruction of microvilli (a condition known as attaching and effacing).
• Enterotoxigenic E. coli (ETEC): The leading cause of travelers' diarrhea and a major cause of diarrheal disease in developing countries, especially in children. ETEC strains produce toxins that stimulate the lining of the intestines causing diarrhea.
• Enteroinvasive E. coli (EIEC): Causes a syndrome that closely resembles shigellosis with bloody diarrhea. EIEC invades and multiplies within the intestinal mucosa.
• Enterohemorrhagic E. coli (EHEC): Known for its outbreak potential, EHEC can cause severe abdominal cramps, bloody diarrhea, and hemolytic uremic syndrome (HUS), a serious condition that can lead to kidney failure. The most infamous EHEC strain is O157:H7.
• Enteroaggregative E. coli (EAEC): Causes persistent diarrhea in children and adults in both developed and developing countries. EAEC strains adhere to the intestinal mucosa in an aggregative pattern.
• Diffusely Adherent E. coli (DAEC): Associated with prolonged diarrhea in children in developing countries. The pathogenic mechanism involves adherence to the intestinal mucosa.

Transmission

Pathogenic E. coli are primarily transmitted through the fecal-oral route. Common sources of infection include contaminated food or water, person-to-person contact, and contact with animals. Outbreaks of pathogenic E. coli infections have been linked to undercooked ground beef, unpasteurized milk and juice, contaminated water, and raw fruits and vegetables.

Symptoms

The symptoms of pathogenic E. coli infections vary depending on the strain but commonly include diarrhea (which may be bloody), abdominal cramps, nausea, vomiting, and fever. In severe cases, particularly with EHEC infections, patients may develop hemolytic uremic syndrome (HUS), leading to kidney failure and potentially death.

Prevention and Treatment

Preventive measures include practicing good hygiene, properly cooking meat, avoiding unpasteurized dairy products and juices, and ensuring safe water supply. Treatment for E. coli infections primarily involves hydration and supportive care. Antibiotics are not recommended for certain types of E. coli infections, such as EHEC, as they may increase the risk of HUS.

See Also

• Microbiology
• Infectious disease
• Foodborne illness
• Hemolytic uremic syndrome

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